Headbox for a papermaking machine



March 21, 1967 F. R. ERBACH 3,310,461

HEADBOX FOR A PAPERMAKING MACHINE Filed. April 20, 1964 2 Sheets-Sheet l yw/z/ w 7 21 I NVENTOR.

fled/53151360012 March 21, 1967 F. R. ERBACH HEADBOX FOR A PAPERMAKING MACHINE Filed A ri; 20, 1964 2 Sheets-Sheet 2 Fed R Erbaalz A T'IY QNE YS United States Patent 3,310,461 HEADBOX FOR A PAPERMAKING MACHINE Fred R. Erbach, Beloit, Wis., assignor to Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Filed Apr. 20, 1964, Ser. No. 360,846 2 Claims. (Cl. 162-344) The present invention relates to improvements in paper machine headboxes and more particularly to a headbox structure for influencing or controlling stock flow in a headbox in advance of the slice opening.

In a pressurized headbox particularly for a high speed papermaking machine, stock flow in advance of the slice opening is important to obtaining good formation and uniformity avoiding flocculation and other disadvantages of poor delivery from the slice. In order to obtain proper flow at the slice the stock must have good formation and a good vertical profile. One manner of obtaining this effect has been to place a foil in the throat area in advance of the slice. This foil spoiled the profile but provided good formation.

It is accordingly an object of the present invention to provide a headbox construction which obtains improved formation and a good profile of stock flow in advance of the slice opening in the headbox throat.

A further object of the invention is to eliminate the provision of a foil in a headbox throat thereby eliminating the spoiled profile caused by the foil, and yet obtain the improved formation offered by the foil but concurrently obtaining a good profile.

A more detailed object of the present invention is to provide an obstruction on the floor of the headbox which extends uniformly across the box with an inclined leading surface and a longer declined trailing surface.

The provision of a foil across the headbox to obtain improved formation and to prevent stagnation and large scale eddy formation has resulted, as above stated, in a spoiled vertical profile, which is also a desirable factor to obtaining proper flow to the slice. The theory of the function and operation of the structure provided in the headbox in accordance with the specific arrangements disclosed below is .as follows but it is to be understood that I do not wish to be bound by this theory but believe that the flow phenomenon occurs because of the improved results obtained. It is theorized that the flow rate and stream center is irregular in a conventional headbox as the flow stream approaches the slice, and is not linear. Providing an obstruction on the floor of the headbox the pattern of flow is upset. In other words, the stream is deflected upwardly and probably this upward flow is caught by the main stream. The obstruction creates uniform flow across the machine at the very location where the obstruction is positioned, and the obstruction absorbs energy and generally slows the flow to equalize it. The portion of the flow which is deflected upwardly is engaged by the main stream above the obstruction to unify the profile in a vertical direction with the eflect on the profile being the same entirely across the width of the box. The mixing of the flow stream portion which is deflected upwardly and the main stream upsets the irregular flow pattern and absorbs energy so that large eddy currents or cross-currents are destroyed and improved formation will result. The stream of improved formation and uniform profile will tend to remain constant as it follows down the declined slope of the obstruction arid moves between the declined slope and the downwardly tapered front wall of the headbox. The stream profile is uniform in a vertical direction and in a direction vertically transverse to the flow stream which now moves in a downward direction toward the slice opening which is substantially parallel to or complementary to the direcice tion of flow of the stock as it passes through the slice opening onto the wire.

Other objects, advantages and features will become more apparent with the further teaching of the principles of the invention in connection with the disclosure of the preferred embodiment thereof in the specification, claims and drawings, in which:

FIGURE 1 is a fragmentary sectional view of a headbox, shown in somewhat schematic form, embodying the principles of the present invention;

FIGURE 2 is an enlarged detailed fragmentary view showing the headbox construction at the slice opening and immediately in advance of the slice;

FIGURE 3 is an enlarged detailed fragmentary view showing a headbox construction at the slice opening of modified form; and

FIGURE 4 is an enlarged detailed fragmentary view showing a headbox construction at the slice opening illustrating another form of the invention.

As shown on the drawings: I

FIGURE 1 illustrates a portion of a papermaking machine wherein a forming surface is supplied by a traveling Fourdrinier wire 10 having a web W formed thereon with the Fourdrinier supported on a breast roll 11. Stock is supplied to the wire 10 by .a headbox 12 having a slice opening 13 through which the stock is emitted.

The headbox is of the closed pressure type having the stock chamber 14 therein defined by the headbox walls, and within the chamber are rectifier rolls 15 and 16. Generally, the headbox may take various forms, and, for example, may be such as that shown in my co-pending patent application, U.S. Ser. No. 360,847, filed April 20, 1964.

The headbox has a rear wall 19 and a forward wall 20 which is declined downwardly toward an upper slice lip 22 which is vertically adjustable. A lower slice lip 21 is positioned beneath the slice opening 13. The headbox has a horizontal floor 18 which extends toward the slice opening.

As shown in greater detail in FIGURE 2, a projection 23 extends upwardly from the floor 18 of the headbox. The projection 23 operates in accordance with the theory above expressed and has a first inclined lead surface 24 which extends upwardly from the floor 18 at an angle or. This angle is preferably in the range of 35 to and faces the oncoming flow stream along the headbox floor to deflect it upwardly into the main stream.

Following the inclined surface 24 is a declined surface 25 which extends downwardly from the tip of the inclined surface 24 to again join the horizontal floor 18. The declined surface is at an angle B with the floor inthe range of 5 to 55". A satisfactory angle for the declined surface is 18 and the declined surface joins the inclined surface 24 in angle of substantially with the angle a of the inclined surface 24 being 72.

The obstruction 23 can readily be formed of fiat stainless steel plates having a highly polished outer surface with the plates of course extending uniformly across the entire width of the headbox. A lower attaching plate 26 may be secured such as by welding to the ends of the plates for the surfaces 24 and 25, and a securing bolt 27 is slid up into the plate which forms the lower lip 21 to hold the obstruction in place. As illustrated, the lower lip is secured in place by bolts 28 which extend through openings in the floor 18. The top edge of the obstruction 23 preferably extends above the lower edge of the upper slice lip 22.

While the structure including the obstruction 23 may be used in headboxes of various designs, in a preferred arrangement the declined surface 25 faces a front wall 20 which declines downwardly toward the slice and the angle of the declined surface 25 is less than the angle of tion 39 mounted thereon.

the front wall 20 so that a slightly tapered throat 29 is provided leading toward the slice opening 13.

FIGURE 3 shows a portion of a headbox 30 having an upper slice lip 31 which is vertically adjustable and a lower slice lip 34 defining a slice opening 33. The headbox has a horizontal floor 35 which extends toward the slice opening 33.

A projection 36 extends upwardly from the floor 18 of the headbox, being of a construction similar to the projection 23 of FIGURE 2. The projection 36 has a first inclined lead surface 37 which extends upwardly from the floor at an angle or with the horizontal planar headbox floor declined surface 38 which extends downwardly from the tip of the inclined surface 37 to again join the horizontal floor 35. The angle of the decline of the surface 38 relative to the horizontal, or relative to the floor, is shown at ,8.

The headbox 30 has a forward wall 32 having a projec- The projection 39 has a leading surface 40 which projects out into the flow stream flowing toward the slice opening 33, and a trailing surface 41. The leading surface 40 forms an angle with the forward headbox wall 32. The trailing wall 41 forms an angle 6 with the headbox forward wall 32.

The projection 39 on the forward wall 32 is constructed to be smaller than the floor projection 36. Also the angles of the leading and trailing surfaces 40 and 41 of the upper projection are constructed to have a relationship to the angles of the surfaces of the lower projection 36, for improved flow characteristics. The angle a (which is the angle between the fioor 35 and the leading surface 37 of the lower projection 36) is substantially equal to the angle 0 (which is the angle between the forward headbox wall 32 and the leading surface 40 of the upper projection 39).

The angle ,8 (which is the angle between the trailing surface 38 of the lower projection 36 and the horizontal floor) is substantially equal to the angle :1) (which is the angle between the front wall 32 and the trailing surface 41 of the upper projection 39).

In FIGURE 4 a headbox 42 has a vertically adjustable upper slice lip 43 and a lower slice lip 44 forming a slice opening 45 therebetween. The headbox has a horizontal floor 46 which is unobstructed.

The headbox has a front wall 47 which carries a projection 48 having a leading surface 49 extending downwardly from the wall 47, and a trailing surface 50 which extends back to the wall 47 from the leading surface 49. The projections 39 in FIGURE 3 and 48 in FIGURE 4 function somewhat the same as the projection on the floor of the headbox to deflect the flow stream outwardly to be caught by the main stream in the manner set forth above.

Thus, it will be seen that I have provided a headbox construction which obtains the objectives and features above set forth. The structure has been found to provide both good'formation and good profile and to avoid disadvantages of structures heretofore obtainable such as with the use of a foil in the throat.

The drawings and specification present a detailed disclosure of the preferred embodiments of the invention, and it is to be understood that the invention is not limited to the specific forms disclosed, but covers all modification, changes and alternative constructions and methods falling within the scope of the principles taught by the invention.

I claim as my invention:

1. A paper machine stock headbox for discharging stock on a travelling forming surface comprising,

a closed headbox chamber with a planar floor and a downwardly inclined forward wall leading toward a slice opening,

a lower projection on the floor ahead of the slice opening extending into the flow stream absorbing energy of the stock flow and deflecting the stream upwardly to be intercepted by the flow stream moving toward the opening,

and an upper projection on the forward wall positioned downstream of the lower projection and being smaller than said lower projection.

2. A paper machine stock headbox for discharging stock on a travelling forming surface comprising:

a headbox chamber with a planar floor and a downwardly inclined forward wall leading toward a slice opening;

a lower projection on the floor ahead of the slice opening extending into the fiow stream absorbing energy from the stock flow and deflecting the stream upwardly to be intercepted by the flow stream moving toward the opening, said lower projection having an inclined surface rising upwardly from the floor facing the flow of stock and having an angle in the range of 35 to with the floor so as to create an improved flow formation in the stock;

and a declined trailing surface following the inclined surface and facing said forward wall of the headbox, said declining trailing surface having an angle with the floor which is less'than said inclined surface so as to maintain the improved flow formation of the stock as the stock is delivered to the slice;

and an upper projection in the forward wall positioned downstream of the lower projection and being smaller than said lower projection and substantially similar thereto.

References Cited by the Examiner UNITED STATES PATENTS 2/1933 Hyde 162 -347 4/1958 Boone et al. 162-216 Assistant Examiners, 

1. A PAPER MACHINE STOCK HEADBOX FOR DISCHARGING STOCK ON A TRAVELLING FORMING SURFACE COMPRISING, A CLOSED HEADBOX CHAMBER WITH A PLANAR FLOOR AND A DOWNWARDLY INCLINED FORWARD WALL LEADING TOWARD A SLICE OPENING, A LOWER PROJECTION ON THE FLOOR AHEAD OF THE SLICE OPENING EXTENDING INTO THE FLOW STREAM ABSORBING ENERGY OF THE STOCK FLOW AND DEFLECTING THE STREAM UPWARDLY TO BE INTERCEPTED BY THE FLOW STREAM MOVING TOWARD THE OPENING, AND AN UPPER PROJECTION ON THE FORWARD WALL POSITIONED DOWNSTREAM OF THE LOWER PROJECTION AND BEING SMALLER THAN SAID LOWER PROJECTION. 